It's also worth considering why this happens, instead of just regarding it as something people do because they're inherently malevolent.
Suppose you suspect your organization of violating some law. You think they're supposed to be using some safety feature on their equipment and they're not, or what have you. In a normal organization, you report this to the leadership and if it's a real problem they fix it, because they know what happens if you report it to law enforcement or it causes someone to get hurt and they don't want that.
Now suppose one of your members reports it to law enforcement instead of the organization's leadership. Government inspectors show up and you have to pay lawyers to deal with them, and lawyers are expensive. Reporters write negative stories about you. These things happen even if the person reporting it was wrong and there was never a real problem. Worse, these outsiders are not always that diligent and you could be prosecuted or dragged through the mud despite the person reporting it being the one who made an error. And if they didn't make an error -- if the problem was real -- that's even worse, because now you're getting convicted instead of having an opportunity to correct the problem. Many laws are even implicitly written under the expectation that honest mistakes are handled internally and only intransigent bastards get reported to the government, so anyone who goes there first is going to be a pariah.
This is legitimately hard to fix because there is a trade off between cost and accuracy. If investigators are more diligent, so they get the result right more often, they have to spend more time finding out what's really going on in an organization they don't come into it with any internal understanding of. Which imposes costs on both the government and the possibly-innocent subject of the investigation. But if they're less diligent then they'll be imposing penalties on innocent people more often. In both cases, any group is not going to want there to be an investigation and is going to be resentful of anyone who causes there to be one.
Governments often make this worse by trying to make it better and imposing penalties on people who fail to report. Because that requirement doesn't eliminate the structural incentive -- if nobody reports then nobody gets punished for not reporting -- but now the group is going to respond with more severe retaliation for reporting because you've just given everyone who didn't report it the incentive to protect the perpetrators to protect themselves and to retaliate against anybody who does.
What you really want here is to do the opposite. Limit the costs and consequences to the unrepentant actual perpetrators, and make sure they're actually guilty, so you don't give the general group the impression that they're all in the same boat and should be collectively fighting against their enemies in the other tribe.